1. Field of the Invention
This invention relates to a data transmission method for interleaved data that may be used for a data recording/reproducing system or a packet communication system wherein interleaved data are transmitted on the transmission channel in conformity with the data format pursuant to, for example, the prescriptions for a compact disk (CD).
2. Description of the Prior Art
Digital/audio disks for music, in which digital/audio data are recorded on the optical disk as the recording medium, such as compact disks or CDs, have become popular. In the CDs for music, a dual coding system employing two series of Reed Solomon codes is adopted as the error correction code system. The data blocks obtained upon digitizing the original audio signals, dividing the resulting digital audio data into groups each consisting of a prescribed number of data and arraying each group of the data two-dimensionally are subjected to an interleaving operation. For example, as shown in FIG. 1, parity codes P are found for data strings of the respective rows of a data block consisting of block data S.sub.1, S.sub.2, . . . , S.sub.27 to form a second Reed Solomon code series C.sub.2. The data of the respective rows, now added to by the parity codes P making up the second Reed Solomon codes C.sub.2 are then subjected to an interleaving operation. In this case, parity codes Q are found for the respective obliquely extending data strings of the two-dimensionally arranged data blocks to form a first Reed Solomon code series C.sub.1. In this manner, cross interleaved Reed-Solomon code or CIRC is formed and transmitted to render the signal processing having high error correction capability possible to provide high-quality reproduced audio signals.
There is also standardized a CD-read only memory or CD-ROM having disk specifications, recording format, modulation system and the error-detection/correction system, in common with the CD for music, and in which the code information is adapted to be written into a data region in which the music information in the CD for music is arrayed. In the CD system for music, data are processed with one frame composed of 588 channel bits as one unit. In the CD-ROM, data are processed with 98 frames as one unit or sector and with the sector addresses introduced into a control signal portion or user bits at the beginning portion of each frame.
The above described CDs for music and CD-ROMS are play-only optical disk on which data are pre-recorded once and for all at the supplier side. There is also evolved and utilized a direct read after write (DRAW) type optical disk on which data can be written at the user side, or an opto-magnetic disk on which both data recording and reproduction are feasible at the user side.
In FIG. 2, the relation between the sector array of the CD-ROM having the disk format conforming to the standards for CDs for music and the array of the interleaved block data is shown schematically. In this figure, unit recording regions or sectors SC.sub.n are indicated by broken lines. To these sectors SC.sub.n are affixed two series of Reed Solomon Codes C.sub.1 and C.sub.2 to data blocks DB.sub.n which are then coded by interleaving so as to lie across three sectors SC.sub.n, SC.sub.n+1 and SC.sub.n+2 as indicated by hatched lines in the figure. Thus, although interleaved data are arrayed in the respective sectors formed on the disk, the data block DB.sub.n is subjected to interleaving so that the data block is arrayed so as to lie across the plural sectors SC .sub.n, SC.sub.n+1 and SC.sub.n+2. In FIG. 2, the data disposed in each sector are divided at intervals of 32 words and arrayed two-dimensionally for illustrating the relation between the sector construction and the interleaved data block. Hence, in the above embodiment, data of the data blocks DB.sub.n cannot be read completely unless the three sectors SC.sub.n, SC.sub.n+1 and SC.sub.n+2 are reproduced. Therefore, when the CD write once read many memory (CD-WORM) or the CD random access memory (CD-RAM) for music having superior compatibility with CD for music or CD-ROM is to be implemented using the DRAW type optical disk or opto-magnetic disk, writing or reading data arrayed in one sector SC.sub.n shown by hatched lines in FIG. 2 influences the Reed Solomon codes C.sub.1 arrayed in the next following sector SC.sub.n+1 and SC.sub.n+2, because of the preceding interleaving operation, so that it becomes necessary to perform a highly complex operation to eliminate the influence in the next following sectors.